1. Field of Invention
The invention is directed towards an integral cutting insert clamping mechanism. More particularly, a mechanism for clamping a cutting insert onto a milling cutter during metalworking operations.
2. Description of Related Art
A number of different types of devices have been used in the past for securing cutting inserts to milling cutters to permit replacement when the cutting insert becomes worn. Many insert clamping mechanisms are directed to a screw being inserted through a screw hole in the cutting insert and threadably engaged into a milling cutter, such as U.S. Pat. No. 5,129,767. However, this clamping arrangement is not suitable for many cutting inserts, especially larger cutting inserts over a half-inch in length and/or cutting inserts whose length is at least twice the width.
The cutting insert is susceptible to breakage at the screw hole because of stress localized near the screw hole. First, during metalworking operations, the forces exerted on the cutting insert from the work piece cause the cutting insert to act as a lever and the screw hole, where the insert is attached to the milling cutter, to act as a fulcrum. The longer the cutting insert the more force which is applied at the location of the screw hole and subsequently increased stress at the screw hole. Second, the screw hole, in of itself, causes stress risers around the screw hole. Third, a downward clamping force by the screw onto the insert adds stress at the location of the screw hole. The localization of stresses, due to applied forces from metalworking and clamping of the cutting insert, at the screw hole causes the cutting insert to be susceptible to breakage at the screw hole.
The weight of a cutting insert is an important factor in metal working. First, during milling it is advantageous to increase revolution per minute (RPM) of the milling cutter to decrease the time to manufacture a work piece. One way to increase the RPM of the milling cutter is to decrease the weight of the cutting insert. If the volume of the cutting insert is decreased so is the weight of the cutting insert and subsequently the higher RPM of the milling cutter. Second, it is advantageous to decrease the cost of the cutting insert. If the volume of the insert is decreased, so is the amount of material to make the insert. The less material that is used to make the insert and subsequently the lower the weight of the cutting insert, the lower the cost of the insert.
Therefore, an object of the present invention is to provide an integral cutting insert clamping mechanism. Further objects of the invention are to provide an integral cutting insert clamping mechanism that: disperses the clamping forces evenly away from the screw hole of the insert to reduce the stress at the screw hole and thereby reduce the susceptibility of breakage at the screw hole, has a substantially planar top surface to reduce the chip evacuation interference on the rake face of the cutting insert, and has a chip breaker.